Method and apparatus for edgewise bending of metal strips



July 10, 1934. R. H. THOMS El AL METHOD AND APPARATUS FOR EDGEWISE BENDING 0F METAL STRIPS Filed May 15, 1929 6 Sheets-SQset l #7 #WIMMW July 10, 1934. R THQMs r AL 1,965,716

METHOD AND APPARATUS FOR EDGEWISE BENDING OF METAL STRIPS Filed May 15, 1929 6 Sheets-Sheet 2 4. I W WW, W 714M,

ATTORNEY July 10, 1934. R. H. THOMS El AL- 1,965,716

METHOD AND APPARATUS FOR EDGEWISE BBNDING 0F METAL STRIPS Filed May 15, 1929 July 10, 1934. R. H. THOMS ET AL 1,965,715

METHOD AND-APPARATUS F013 EDGEWISE BENDING OF METAL STRIPS Filed May 15, 1929 6 Sheets-Sheet 4 V//////////////////////// lif/ NNNNNNN R S W WW ATTORNEY 6 sneets sheet 5 R. H. THOMS El" AL Filed May 15. 1929 METHOD AND APPARATUS FOR EDGEWISE BENDING 0F METAL STRIPS July 10, 1934.

July 10, 1934. R. H. THOMS n AL.

METHOD AND-APPARATUS FOR EDGEWISE BENDING 0F METAL STRIPS Filed May 15, 1929 6 Sheets-Sheet 6 Patented July 10, 1934 UNITED STATES METHOD AND APPARATUS FOR EDGEWISE BENDING OF METAL STRIPS Rudolph H. Thoma and Robert H. Maddock, Cleveland.'0hio, assignors to Midland Steel Products Company, Cleveland, Ohio, at corporation of Ohio Application May 15, 1929, Serial No. 363,271

16 Claims.

This invention relates to a method of bending flat metal sheets or strips edgewise, i. e. within the plane thereof, and to an apparatus for carrying out the steps of this method.

In the preparation of blanks of thin strips of metal, such, for example, as the formation of blanks for automobile side frames, 2. common practice is to cut a rectangular strip from a sheet and from this cut a blank, curved approximately waste of material, whereas'if rectangular strips are cut from the sheet and then bent to the desired shape for final formation, narrower strips may be used and waste of metal in trim largely eliminated.

One of the difficulties encountered in forming curved edge strips of the shape desired from straight edge strips, by edgewise or fiat bending, is distortion of the metal in the plane of the sheet 20 or strip. To prevent transverse distortion, the strip must be closely confined. This confining of the strip, while giving the bending motion parallel with its plane, presents many dimculties. For example, in attempting to make such bends by the use of a slot-like die containing the thin strip and a male knife-like die of approximately the thickness of the sheet or strip, the edges of which die are curved to the desired formation, the male die is very fragile and breaks or ships, destroying its usefulness.

Other methods include gripping the sheet on its fiat surfaces very tightly between dies having opposed shoulders of the desired curvature, and while tightly gripping it, moving die parts with relation to each other and to the strip. The tight gripping incident to this requires much greater power for the means actuating the dies, and the two-way movement of the dies for gripping and bending requires additional attendant mechanisms. A more serious objection to the method of tightly holding the sheet while distorting it in its plane, is that the structure of the sheet is weakened by undue stretching of certain of its portions between the parts moved relatively.

The present invention provides an apparatus for carrying out this process. It is intended to confine but not grip or compress the sheet, whereby a further'object is accomplished.

In the making of side frame members for autoblanks, such as illustrated in the drawings, are

flanged by turning to a normal position with relation to the body of the blank. The result of this is that on the concave curve the edge of the blank is necessarily stretched, while the convex perimto the shape desired. This method results in.

mobiles for example, the marginal edges of the eter is correspondingly shortened or compressed in the fianging die. By the present invention I overcome the incident difliculties such as the stretching or tearing of the metal on the concave side by causing a thickening of the sheet during the edgewise bending, due to the fact that the bending dies, hinging of the edge thereof upset the metal in a tapered or wedge-like section to substantially the distance between the confining surfaces. These surfaces do not grip the blank and so permit the upsetting desired. The convex curve having been stretched during the edgewise bending, as it is flanged and thus shortened, again thickens and produces a substantially uniform section without tearing or wrinkling the metal.

A further object of the invention is to provide an arrangement of die parts which shall automatically confine the strip and bend it without gripping it, and upon the return movement automatically open to release the sheet for freedom of removal and corresponding freedom of insertion of a subsequent sheet or strip.

A more specific object is to provide such an arrangement of die parts that they may be used in any simple reciprocating press requiring no special equipment other than the die parts themselves, and to produce a die apparatus which is capable of simple construction of die parts, each having suflicient body and thickness to be very durable.

Other more specific objects will become apparent from the following description which relates to the accompanying drawings.

In the drawings- Fig. 1 is a longitudinal section through the die showing the strip blank in place before bend- Fig. 2 is a similar section showing the dies closed after the bending operation;

Fig. 3 is an enlarged transverse section taken substantially on the plane indicated by the line 33, Fig. 1.

Fig. 4 is a still further enlarged section taken as indicated by the line 44 on Fig. 2, showing the dies in closed position;

Fig. 5 is another transverse section taken at the central portion of the die parts, as indicated by the line 55 of Fig. 2;

Fig. 6 is a transverse section taken near the end of the die parts as indicated by the line 66 on Fig. 2;

Fig. '7 is still another transverse section on the same scale as Fig. 5, as indicated by the line 7--7 of Fig. 2; Figs. 5, 6 and 7 each showing a complete base or frame and head member and slide carrier for one ofthe female die parts;

Fig. 8 is a transverse sectional die illustrating springs actuating one-of the female die parts to open, the position of the section beingindicatedbytheline8-8ofFigure2; Fig. 9 is a plane view of the assembled die parts showing the essential elements in broken lines beneath the head;

Fig. 10 is a sectional view taken substantially on lines 10-10 of Figs. 5 and 9, looking toward the die parts there shown in broken lines;

Fig. 11 is a diagrammatic illustration of a blank to be flanged, illustrating the changes in the lengths of the edges during the bending and hanging operations;

Fig. 12 comprises a series of diagrammatical sections as indicated correspondingly on Fig. 11, showing the relative thicknesses of the opposite edges of the blank after bending;

Fig. 13 illustrates a blank after bending, taken at the center of the curve or. bend and showing the upset or wedge taper before bending and the approximate shape of the flanged frame member.

In the following description reference is made to the drawings by the use of numerals, the same numerals indicating the same parts in the different figures.

. For the purpose of illustration we have shown in the drawings a form of our invention adapted for use in connection with a die bending machine of the usual form, of whichthe principal parts are a frame 1, a vertically movable head member 2 actuated by power means, not shown, and vertically movable supporting posts, not shown, in-

termediate and connecting frame 1 and movable head member 2, die members 3, 4 and 5 secured to and carried by the movable head member, complementary die members 6 and 7 secured to a spacing and supporting block 8 attached to the frame 1.

As here shown, our invention includes a carrier plate 9 extending longitudinally with reference to the machine, having an inwardly facing surface normal to the bending faces of the dies 3, 4, 5, 6 and 7. This is secured to the movable head member 2 by suitable means shown as bolts 10, and is carried by the head member 2.

Means are provided to support carrier plate 9 against any outward lateral thrust, but to allow it concurrent movement in a directed path, here shown as vertical. A preferred form of such means appears in the drawings and includes a series of slide plates of hardened material, desig'nated 12, 14, 18 and 20, secured by suitable means, such as by bolts 21, to the outward surface of carrier plate 9 at convenient intervals. These are arranged to bear against complementary slide plates 11, 13, 15, 17 and 19 respectively, and to cooperate with the latter to form sliding supports for the carrier plate 9. The latter series of plates are secured to the frame 1 of the machine by suitable means such as bolts 22,-preferably at the supporting posts or bosses 23, 24, 25, 26(A) and 27 of the frame 1.

The material to be operated upon, designated 8, is shown as a flat, thin, metal strip, rectangular in cross section, in position for edgewise bending. The inward face of the carrier plate 9 is formed so as to furnish a smooth surface against which the adjacent surface of the material S to be operated upon is supported during the desired stages of the bending operation. Furthermore, it is formed to furnish a partial guide and support for the material 8, while the material is being inserted into or removed from the machine prior to or following the bending operation.

A preferred and economical manner of forming such a surface so that it is replaceable, includes a series of face plates of hardenedmaterial, 28, 29,

' 30, 34 and 35 so arranged that their inward surdie members 3, 4, 5, 6 and 7 are of a width such as strength and durability require, and overlap the face plates 28, 29, 30, 34 and 35, so that the inward surfaces formed by these plates fall near the longitudinal center line of the die members -and remote from the lateral edges.

A preferred and convenient means to continue the supporting surface integral-at dies 6 and 7 at all times during the operation of the machine and at the sometime to allow the blank S to rest on the middle portions of the dies 8 and 7, include two sliding face plates 34 and 35. The lower portions of these plates are formed to fit the bending faces of the dies 6 and 7 respectively, on which the plates rest at all times during the.operation of the thus furnishing a partial guide and a support for the blank strips or sheets S during their insertion into and removal from the dies. These plates are supported longitudinally and laterally but are free to move edgewise (as shown) relative to plates 9 and 2, normal to the bending surfaces of the dies.

Referring to the sliding face plates 34 and 35, suitable means for obtadning such support is shown at 36, 37, 43 and 44, as the conventional slides and cooperating guide ways. Projecting stops 40 and 45 operate in slots 39 and 46'respectively to prevent the sliding face plates from becoming disengaged when the movable head mem her 2 is raised for repairing, etc. Suitable openings 38 and 42 in the movable head member 2 permit passage of the sliding face plates 34 and 35 relative to the movable head member 2. The member designated as 48 is a carrier plate having an inward siu'face formed into a single plane parallel to and preferably identical in form with the inward surface of the carrier plate 9. As

shown, such surface is obtained by the use of face plates 49, 50 and 51 secured to the carrier plate 48 by groups of bolts 54, 55, 56; and sliding face plates 52, and 53, which operate in cooperating guideways 59 and 60. These sliding face plates may be identical in form and operation with the corresponding sliding face plates 34 and 35,respectively, of carrier plate 9. The openings 38 and 42 are large enough to permit relative passage of .these sliding faces and the removable head member 2. 1

At convenient intervals along the carrier plate 48 means are provided to support it and at the same time to allow it a limited lateral movement for opening and closing the 'dies. A suitable form of such means includes supporting slides 61, 62, 63, 64 and 65 having respectively slide head portions 66, 67, 68, 69, 70, which act as flanges to engage in and cooperate with complementary guideways 71, 72, 73, 74 and 75 respectively in the movable head member 2. The inward movement attached member.

of the carrier plate 48 is stopped by the resilient return means, a convenient form of which is shown at 157 and 158 and includes springs supported between and abutting carrier plates 9 and 48. Means are provided to move the carrier plate inwardly coordinately with the operation of the machine, and to support it laterally when it has reached its most inward position.

As here shown such means are a series of sliding cam plates 120, 121, 122, 123 and 124 secured to the carrier plate 48 at convenient positions, so as to cooperate with the complementary sliding wedge plates 83, 84,85, 86 and 87 respectively, which latter are secured to the frame of the machine at supporting posts or bosses78, '79, 80, 81 and 82 respectively. It is desirable to form the cam portions of the respective pairs of sliding cam plates across the central positions of their respective faces, as shown at 112, 113, 94, 114, and 138, 139, 128, 140 and 141, so that the can'ier plate does not move inward until just before the movable die members 3, 4 and 5 contact with the edge of the blank material S. The sliding surfaces of the cam plates adjoining the wedge portions support the carrier plate 48 laterally after the wedge portions have thrust it to its innermost position.

We now describe the operation of this apparatus in carrying out this process. Figs. 1, 3, 4 and 9 show the apparatus in position to start the bending operation, the movable head member and the attached carrier plates being raised and the latter held apart by the return means. The sliding face plates 34, 35, 52, 53, are restingon the dies 6 and '7 respectively. While the apparatus is in this position the blank material S is inserted, being guided along the bending faces of the dies 6 and '7 and positioned by the sliding face plates so that it rests edgewise on the die faces approximately in place. Power is then applied and the movable head member 2 moves downwardly, carrying with it'the movable die members 3, 4 and 5, and the carrier plates 9 and 48 with their As it moves downward the sliding cam plates force the carrier plate 48 inwardly, narrowing the opening between the carrier plates and, shoving the blank material 8 into position for bending, and compressing the resilient return means 157 and 158. The inward movement of carrier plate 48 continues until the sliding surfaces of the attached sliding cam plates cooperate with the sliding surfaces of their complementary sliding cam plates respectively. Here the offset plane surfaces of the cam plates very rigidly hold the die surfaces in operative position over the entire area of the blank being bent.

At this stage in the operation the material S is in position for bending, resting on edge on the stationary die members 6 and 7 and confined laterally by the inner surfaces of the carrier plates 9 and 48. As shown in Fig. 4 the blank material S rests approximately along the longitudinal center line of the stationary die members 6 and 7, confined as stated. It is neither gripped nor compressed but is free to move edgewise. In Fig. 4 the clearance between the confining face plates and the material is exaggerated for the purpose of more clear illustration. In actual practice this clearance is preferably only a few thousandths of an inch.

While thus confined the movable die members contact with the blank material, bending it across the stationary dies 6 and '7. The same clearance that prevents friction, abrasion and destructive strain of the blank S as it bends downwardly,

as stated above, also permits the blank strip 8 to slide longitudinally to compensate'for the shortening due to the bend.

As soon as the blank material S is bent as desired, the movable head member 2 and thecarrier plates are withdrawn, the sliding face plates remain in a, position resting on the stationary dies. As soon as the sliding wedge plates release the carrier plate 48, the return means, that is, the springs 146, force it outward and the opening between the dies is enlarged so this material may be removed readily, and a fresh blank easily inserted.

Referring now to Figs. 11, 12 and 13 as stated, the slightly separated confining walls permit the material to upset at the concave bends and stretch freely at the convex bends. The small sections A, B, C, D and E taken along corresponding lines in Fig. 11 serve to illustrate this. It should be noted that the end dies contact with a longer portion of the edge of the strip thanthe curved dies, and hence cause negligible upsetting'at such portions, as shown in Fig. 13, A and E. However, at B, C and D, Fig. 13, the upsetting and stretching is very noticeable. The more sharply the bend is curved, the more the material is upset on the concave side and stretched on the convex, due to the increased working force.

However, the relative change of radius is greater when flanges are turned on sharp bends and consequently on the concave side of such bends more material is required to compensate for this. On the convex side more excess material would be formed. The upsetting and stretching here caused thus changes directly proportionately to the amounts required. The lines a and b, Fig. 11, show the strip edges at a position before turning the flanges. The dotted lines a and b show the same edges after turning the flanges. The radii R RQRF, and R" show respective changes in the radii of the corresponding sides, due to flanging. The small triangular sections B C and D show the excess material consequent upon turning flanges at the convex portion of the bends. These are largely absorbed by increasing the thickness of the flanges, and since such portions have previously been stretched, the flange is brought to a size close to that of the original thickness of the strip, as illustrated at a and b, Fig. 13. The triangular sections B C and D show the deficiencies of the material consequent upon turning the. flanges at the concave portions of the bends. The additional thickening due to upsetting the material compensates for these by stretching when the flange is turned and furnishes the material required, and brings the upset edge back to approximately its thickness before upsetting.

It is to be understood that the arrangement of the parts of such a die apparatus, as herein shown and described, may be subject to various modifications in the carrying out of our process, without departing from the spirit of these inventions, the essential characteristics of which are summarized in the appended claims.

We claim:

1. An apparatus for bending flat, thin metal strips in the plane thereof, including-relatively movable head and frame members, bending elements in staggered relationship secured to said members and engaging edges of the strip, confining elements carried by one of said members, surfaces formed on the other of said members to tive movement of said head and frame members, and means to actuate said confining elements relatively toward and away from each other consequent upon the relative movement of said headand frame members. 1

2. An apparatus for bending fiat, thin metal I strips in the plane thereof, including relative movable head and frame members, bending elements in staggered relationship secured to said memfaces formed on the other of said members to embrace said confining elements during the relative movement of said head and frame members, cam means to actuate said confining elements relatively toward each other consequent upon the relative movement of said head and frame -members, and means to return said confining tive'mo'vement of said head and frame members,

one set ofsaid embracing elements having surfaces in the same plane, the opposite set having surfaces in a plurality of planes connected by cam surfaces, one of said confirming elements having surfacesin one plane to cooperate with the embracing element havingsurfaces in one plane, .the other confining element having surfaces in a plurality of planes connected by cam surfaces cooperating with the embracing elements having a plurality of parallel surfaces connected by cam'surfaces, to move said confining elements relatively together consequent upon the relative movement of the head and frame members, and means to return said confining elements to their original positions.

4. An apparatus for bending fiat, thin metal strips in the plane thereof, including relatively movable head and frame members, bending elements in staggered relationship secured to said members and engaging edges of the strip, confining elements carried by one of said members, embracing elements on the other of said members to embrace said confining elements during the relative movement of said head and frame members, one set of said embracing elements having surfaces in the same plane, the opposite set'having surfaces in a plurality of planes connected by cam surfaces, one of said confining elements having surfaces in one plane to cooperate with the embracing element having surfaces in one plane, the other confining element having surfaces in a plurality of planes connected by cam surfaces cooperating with the embracing element,

having a plurality ofsurfaces connected by cam surfaces, to move the confining element having cam surfaces toward and away from the other confining element consequent upon the relative movement of the head and frame members, and to support the confining element having cam surfaces at its inward position during part of the bending operation, means to return the said confining element having the cam surfaces to its original position when the head and frame membersare moved relatively apart.

5. An apparatus for bending fiat, thin metal strips in the plane thereof, including relatively resume embracesaid confining elements during the rela-' movable head and frame members;' bending eleing elements carried by, one of said members, said bending elements bridging the space between said confining elements and overlapping the edges of said confining elements, and means to actuate said confining elements relatively toward and away from each other consequent upon the relative movement of said head and frame members. I 6. An apparatus for bending fiat, thin metal strips in the plane thereof, including relatively movable head and frame members, a. confining element carried by one of said members, said confining element having surfaces thereon formed in parallel'planes to engage similar surfaces on the other of said members, a second confining element carried by one of said members and having surfaces formed in parallel planes connected by cam surfaces to engage similar surfaces formed on the other of said members to cause relative movement together of said confining elements consequent upon the relative movement of the head and frame members, dies in staggered relationship carried by said head and frame members,

respectively to engage the edges of the strip, means to move saidconfining elements relatively apart on reverse relative movement of said head and frame members, means carrying one of said confining elements and permitting movement thereof toward and from the bending elements.

'7. An apparatus forbending flat, thin metal strips in the'plane thereof, including relatively ments in staggered relationship secured to said members and engaging the edges of the strip, confining elements carried by one of said members,

said confining elements'having surface sections stationary relative to adjacent dies'in their normal confining planes, and means to actuate said confining elements relatively toward and away movable, head and frame members, bending elefrom each other consequent upon the relative movement of said head and frame members.

8. An apparatusfor bending fiat, thin metal strips in the plane thereof, including relatively movable head and frame members, bendingplements-in staggered relationship secured to said actuate said confining elements relatively toward and away from each other consequent upon the relative movement of said head and frame members.

9. An apparatus for bending flat, thin metal strips in the plane thereof, including relatively movable head and frame members, bending elements in staggered relationship secured to said members and engaging the edges of the strip,

- confining elements carried by one of said members, saidconfining elements having surface sections stationary relative to adjacent bending elements in their normal confining planes, and normally resting against the bending elements and slidable transversely thereof during relative movement of the head and frame, said bending elements bridging the space between and overlapping the edges of said confining elements, and

means to actuate said confining elements, relatively toward and away from each other conse- 50 quent upon the relative movement of said head and frame members.

10. An apparatus for bending flat, thin metal strips in the plane thereof, including relatively movable head and frame members, bending elements in staggered relationship secured to said members and engaging edges of the strip, confining elements carried by one of said members, said confining elements having complementary adjacent surfaces arranged to move along with portions of the sides of the strip at and in a direction of part of the bend, and stationary surfaces at other portions of the sides of the strip, said confining elements being stationary relative to each other in the direction of the bend, and means to actuate said confining members toward and away from each other consequent upon the relative movement of said head and frame elements.

11. An apparatus for bending fiat, thin metal strips in the plane thereof, includingrelatively movable head and frame members, bending elements in staggered relationship secured to said members and engaging edges of the strip, confining elements carried by one of said members, means mounting one of said confining elements permitting relative movement of said elements transversely of the confining plane, and means to actuate said confining elements toward and away from each other consequent upon the relative movement of said head and frame members.

12. Anapparatus for bending flat, thin metal strips in the plane thereof, including relatively movable head and frame members, bending ele-v ments in staggered relationship secured to said members and engaging edges of the strip, confining elements carried by one of said members, means mounting one of said confining elements permitting relative movement of said elements transversely of the confining plane, said means including a slide extending transversely of the confining planes, means to actuate said confining elements toward each other, and means to return said elements to their outward position, consequent upon the relative movement of said head and frame members.

13. An apparatus for bending flat, thin metal strips in the plane thereof, including relatively movable head and frame members, bending elements in staggered relationship secured to said members and engaging edges of the strip, confining elements carried by one of said members, said confining elements having longitudinally spaced surface sections relatively movable in their planes, the said sections remaining stationary in their planes relative to adjacent bending elements, and means to actuate said confining members toward and away from each other consequent upon the relative movement of said head and frame elements.

14. An apparatus for bending fiat, thin metal strips in the plane thereof, including relatively movable head and frame members, bending elements in staggered relationship secured to said members and engaging edges of the strip, confining elements carried by one of said members, said confining elements having longitudinally spaced surface sections relatively movable in their planes, said relatively movable sections having stop shoulders limiting their movement relative to their mounting, and means to actuate said confining elements toward and away from each other consequent upon the relative movement of said head and frame members.

15. An apparatus for bending fiat, thin metal strips in the plane thereof, including relatively movable head and frame members, bending elements in staggered relationship secured to said members and engaging edges of the strip, confining elements carried by one of said members, said confining elements having longitudinally spaced surface sections relatively movable in their planes, the said sections remaining stationary in their planes relative to adjacent bending elements, some of said sections resting on surfaces of the adjacent bending elements, and

means to actuate said confining members toward and away from each other consequent upon the relative movement of said head and frame members.

16. The process of forming curved strip blanks from flat thin strip metal of substantially rectangular outline, which includes the steps of loosely supporting the flat sides of the blank against any lateral distortion greater than a very small percentage of the thickness of the blank for permitting the material of the blank to travel longitudinally to compensate for shortening of the overall length and for bending edgewise unresisted by frictional forces tending to cause tearing of the metal as the blank is offset edgewise, and concurrently subjecting the opposite edges of the blank to edgewise pressure at separated sectors in staggered relationship to each other for eflecting the edgewise offset of the blank to form the curved blank.

RUDOLPH H. THOMS. ROBERT H. MADDOCK. 

